Is direct microwave heating well suited for sintering ceramics?

This paper presents a thorough analysis of direct microwave heating as sintering process ceramic materials. It questions why susceptor-assisted is used in most experimental works, although coupling preferable for taking advantage the possible beneficial effects field on phenomena. issue was investigated by conducting both experiments and numerical simulations. The consisted alumina yttria doped zirconia powder samples 2.45 GHz resonant cavity with automatic thermal monitoring, whereas simulations coupled electromagnetics, transfer sample deformation. Alumina are widely materials they exhibit different behaviours (transparent absorbent, respectively), which representative influence insulating material discussed considering cell designs. very low capacity made its difficult. therefore necessary to apply strong electric heat it. situation promoted absorption energy other elements such material, leading instabilities degradation insulation cell. In case zirconia, properties change abruptly increasing temperature. poorly absorbent at temperature, highly intermediate temperature it finally becomes reflective end process. consequences this behaviour (i) difficult control (ii) propensity form damaging hot spots (iii) impossibility reach high temperatures without forming plasma. Therefore, study showed that not suitable reliable homogeneous classical ceramics. explains time preferred.